The present invention relates to apparatus and methods for inserting an intraocular lens through a small incision into an eye. More particularly, the invention relates to such apparatus and methods utilizing a plunger to displace an intraocular lens through a tubular insertion apparatus, wherein the intraocular lens is reliably and safely engaged by the plunger.
An intraocular lens (IOL) is implanted in the eye, for example, as a replacement for the natural crystalline lens after cataract surgery or to alter the optical properties of (provide vision correction to) an eye in which the natural lens remains. IOLs often include an optic, and preferably at least one flexible fixation member or haptic, which extends from the optic and becomes affixed in the eye to secure the lens in position. The optic normally includes an optically clear lens. Implantation of such IOLs into the eye often involves making an incision in the eye. Making the incision as small as possible reduces trauma and speeds healing.
IOLs are known which are foldable (deformable) so that the IOL can be inserted into the eye through an incision smaller than the diameter of the lens.
Some of the most generally accepted insertion apparatus employ a hollow insertion tube having a diameter which permits the folded IOL to pass freely through the tube without permanent deformation, and without causing the surgeon to apply excessive force to overcome friction between the walls of the insertion tube and the IOL. Excessive force can result in the premature ejection of the IOL before the surgeon is ready to position it within the patient""s eye. Such an apparatus can be seen in Brady, U.S. Pat. No. 5,702,402. It would be advantageous to provide IOL insertion apparatus and methods which facilitate the passage of a folded IOL through the apparatus and the insertion of the IOL in the eye in easy, effective and controlled manner while avoiding damage to the IOL and undue trauma to the patient.
In these generally accepted apparatuses, the insertion tube is held in a handpiece which is coupled to a plunger rod. The plunger rod is moved distally through the insertion tube to urge the IOL to pass through the tube and into the eye.
An intraocular lens insertion apparatus of this type is disclosed in Brown, et al., U.S. Pat. No. 6,010,510, and includes an injector plunger having a blunt, rounded tip offset from the centerline of the plunger rod. The offset tip assures that the tip is biased downward against the bottom of the cartridge bore to help ensure proper engagement of the intraocular lens therein. However, there is a possibility that the plunger tip might ride underneath or otherwise fail to engage the intraocular lens.
There is thus a need for a more effective and safe means for engaging and displacing an intraocular lens from within an insertion apparatus.
The present invention provides an improved apparatus for inserting an intraocular lens through an incision into an eye. The apparatus operates in an environment that is similar to existing systems, with a cartridge being loaded into a handpiece, and plunger rod of the handpiece extending through a lumen in the cartridge to push an intraocular lens from an injection tube of the cartridge through an incision in the eye. The apparatus of the present invention provides structure within the cartridge and on the plunger rod that ensures positive engagement between the plunger rod and the intraocular lens to more reliably advance the intraocular lens into the eye in the desired orientation.
In one embodiment of the invention, an apparatus for inserting a foldable intraocular lens through an incision into an eye includes a cartridge having a longitudinal lumen generally arranged along an axis. The cartridge has a distal injection tube terminating in a mouth opening to the lumen, and a proximal loading end having a generally cylindrical inner surface defining a load chamber sized to contain an intraocular lens and form part of the lumen. The load chamber is configured to cause the foldable intraocular lens to conform around the inner surface substantially in a first curvature to define an inner lens face and an outer lens face. The load chamber is further configured to form a section of the intraocular lens having a second curvature centered outward of the outer lens face.
The inner surface may be radially stepped to form the section of the intraocular lens having the second curvature. In one embodiment, the inner surface of the loading end is defined by opposed arcuate walls having different radii of curvature, wherein the radially stepped configuration of the inner surface is formed between adjacent axially extending ends of the arcuate walls. Desirably, the cartridge is a folding-type cartridge with the opposed arcuate walls connected at a hinge. Furthermore, the arcuate walls may be aligned at adjacent axially extending first ends and misaligned at adjacent axially extending second ends, such that the second ends define the radially stepped configuration of the inner surface.
Another aspect of the present invention is an intraocular lens insertion apparatus comprising a cartridge, a handpiece for receiving the cartridge, and a plunger rod coupled to the handpiece. The cartridge has a non-tubular load chamber for receiving an intraocular lens defined by a generally arcuate inner surface interrupted by a radial step. The plunger rod is adapted to be displaced into the load chamber adjacent the radial step. The plunger rod may include an intraocular lens engaging end having a pair of spaced lips, wherein a first lip is aligned to pass directly over the radial step and a second lip is spaced toward an axis of load chamber. Desirably, the radial step defines a shoulder projecting into the load chamber to which the intraocular lens conforms. The shoulder is stepped radially inward from an adjacent portion of the arcuate inner surface to which the intraocular lens also conforms such that the lens is caused to curve radially inward at a section between the shoulder and the adjacent portion. In this regard, the first lip is aligned to pass over both the shoulder and the adjacent portion and transversely intersect the thickness of the intraocular lens at the section that curves radially inward. Again, the cartridge of the system may be a folding-type cartridge with a pair of opposed arcuate walls and a hinge enabling relative pivoting of the walls. The arcuate walls are opened to permit placement of the intraocular lens in an unfolded state on the inner surface, and walls may then be closed to create the load chamber and fold the intraocular lens therewithin.
These and other aspects of the present invention will become apparent in the following detailed description and claims, particularly when considered in conjunction with the accompanying drawings in which like parts bear like reference numerals.